docs: def __get_registry_key(self, key):
          """ Read currency from windows registry """
          import winreg
  
          root = winreg.OpenKey(
              winreg.HKEY_CURRENT_USER, r'SOFTWARE\GSettings\org\gnucash\general', 0, winreg.KEY_READ)
          [pathname, regtype] = (winreg.QueryValueEx(root, key))
          winreg.CloseKey(root)
          return pathname